[AMPS] Amperex

[Garry & Yelena]

Your comments about Amperex graphite Z's were interesting--especially
about their having a mu of 200 in 1969. I don't think the tubes I bought
from Richardson in 1992 had anything like that value.

I popped the pair--with 1990 date codes--into my L4B and re-tweaked the
input circuits. I was appalled to discover that my 100+ Watts of drive
could not drive these tubes to full rated plate current or grid
current.  They appeared to be quite deficient in gain--10 dB power gain
for the PAIR on the best band--and I returned them. Richardson replaced
them from stock, but the condition was unchanged. I then attempted to
engage them in dialogue about it, pointing out that their data sheet
claimed the same specs as Eimac's. I quickly exhausted the salesman's
bullshit reserve and he promised a call from a factory engineer. That
never came, despite my repeated and insistent requests. The salesman
thought it had to be my amp--but I swapped tubes in that amp and with
another amp, and the insufficiency followed the tubes.

They blew me off, plain and simple. I ate the tubes, using them until
recently, when I replaced them with standard Eimacs. Voila--operating
points for the Eimacs were as claimed in the data sheet. Needless to
say, Richardson saw the last of me.

I gather that more recent Amperexes behave better.
-- 
Garry Shapiro, NI6T
Editor, "The DXer," newsletter of the NCDXC
Visit the Northern California DX Club 50th Anniversary page:
http://www.aa6g.org/ncdxc50.html

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